Rotary drain and sewer cleaners have been utilized to clear obstructed sewer or drain lines clogged, for example, by sewage waste, by penetrating tree roots, etc. Such cleaning apparatus includes a frame with a drum rotatably mounted thereon. One end of a flexible elongate cable or snake is attached inside the drum and a portion thereof is wound inside the drum and exits the drum through a feeder. A cutter is attachable to an opposite end of the elongate cable. Typically, a motor with a belt/pulley drive rotates the drum. As the motor rotates the drum, an operator inserts the elongate cable into the drain or sewer line. Usually the obstructions are cleared by a combination of an inward movement of the elongate cable caused by the operator and the rotation of the cutter caused by the motor.
However, a dangerous condition occurs if the cutter becomes engaged with the obstruction and the obstruction restricts further rotation of the elongate cable by the motor. The strain caused by further rotation of the motor can damage the cutter or break the elongate cable. Such a condition could harm the operator if the elongate cable breaks adjacent an opening to the drain or sewer line. When the cable breaks, the torque on the motor instantaneously goes from very high to very low causing the broken end of the cable to whip.
Prior art rotary drain and sewer cleaners limit torque applied to the elongate cable and cutter by employing a slip-type clutch between the motor and the drum. Since torque limitations for both cutters and elongate cables are known, the prior art rotary drain and sewer cleaners utilize a slip-type clutch which slips just below these torque limitations. However, these slip-type clutches wear, are unreliable, and fail to provide an audible or visible indication of a high torque condition. These prior art cleaners may provide excess torque if improperly adjusted or insufficient torque due to wear.